Parasitology Flashcards
Stomoxys calcitrans is known by which other name?
Stable fly
Which flies cause sweet itch in horses?
Culicoides
How long is the cyathostomin life cycle?
6-8 weeks
The classification of strongyles into ‘large’ or ‘small’ depends on the size of what?
The mouthpiece
What is meant by the prepatent stage?
The time between picking up larvae and passing out eggs in faeces
In the cyathostomin life cycle, which larvae stage is ingested by the horse?
L3
In the cyathostomin life cycle, stahe L2 has a protective sheath, but where is it lost?
Small intestine of the horse
In which stage of the cyathostomin life cycle would you expect a horse to show clinical signs?
EL3
What are the clinical signs of cyathostomins?
Oedema Diarrhoea Colic Weight loss 50% mortality Often seen in naive young animals
What is meant by hypobiosis?
Inhibited larval development within the host
In the cyathostomin life cycle, when is the highest shedding of eggs?
August
In the cyathostomin life cycle, when is there a peak of L3 on pasture?
Late summer (August/September)
Name 4 anthelmintics used to treat cyathostomins?
Ivermectin
Moxidectin
Benzimidazoles
Pyrantel
How is the type of disease (acute, sub-acute or chronic) determined with fasciola hepatica?
Determined by number of metacercariae ingested and the time period over which they were ingested
How could you identify acute fasciolosis in the liver of an affected sheep?
Visible multifocal necrotic or haemorrhagic tracts can be seen throughout the liver (of migrating juvenile flukes)
What are the clinical signs of acute fasciolosis?
What animal does it typically affect?
When does it occur?
Sheep
Sudden death, weakness/dullness, abdominal pain, anaemia
Juvenile flukes migrating through liver parenchyma causes multifocal necrotic or haemorrhagic tracts
October-January
What are the clinical signs of sub-acute fasciolosis?
How is it caused?
Rapid weight loss, anaemia
Sheep ingest metacercariae over a longer period of time
What are the clinical signs of chronic fasciolosis?
Which animals does it affect?
How does it happen?
When does disease occur?
Progressive weight loss, anaemia, sub-mandibular oedema, ascites
Sheep and cattle
Low numbers of metacercariae ingested over a longer period of time
Disease in late winter/early spring: Jan/March
Name 3 ways you can diagnose a fluke infection?
Faecal egg counts Post-mortem Clinical signs Copro-antigen ELISA Antibody detection ELISA
Which drug is typically used to treat fluke?
Triclabendazole
Name the 3 classes of anthelmintics, and name a drug from each class
- Benzimidazoles- Panacur (fenbendazole), triclabendazole
- Imidathiazoles/ tetrahydroprimidines- levamisole, Pyrantel
- Macrocyclic lactones- avermectins eg ivermectin, milbemycins eg Moxidectin
Which animals are the primary source of toxiplasma gondii infection in sheep?
Cats shed oocysts in pastures
What is meant by refugia?
The proportion of a parasite population that is not selected by drug treatment (in refuge from a drug)
What is a parasite?
An organism that is dependent metabolically on another, where that organism benefits at the expense of the other
An arthropod is classed as an invertebrate animal having what?
An external waterproof skeleton which is mainly made of a-chitin
A segmented body
Jointed limbs
A haemocoel-the body cavity which contains haemolymph (blood)
What is the name of the system which filters waste from the haemolymph into the gut in arthropods (insects and arachnids)?
Malpighian tubules
What are the two types of arthropod life cycle?
Holometabolous-complete metamorphosis eg flies
Hemimetabolous-incomplete metamorphosis eg ticks and lice
Which macrocyclic lactone has a zero milk withdrawal period?
Eprinomectin
Which areas of a horses body are affected by sweet itch?
Self-inflicted lesions on the withers, mane, tail, face
Culicoides are vectors of which viruses?
Bluetongue (cattle, sheep) Schmallenberg (calves and lambs) Epizootic Haemorrhagic Fever (deer and livestock) Bovine Ephemeral fever (cattle) Transmit African Horse Sickness
Which word is given to the process where fly larvae invades and feeds on living or necrotic tissue?
Myiasis
How long is the life cycle of Culicoides (biting midges)?
Eggs to adults in 3 weeks, can be less in warmer climates
What are the clinical signs of sweet itch in horses?
Pruritic dermatitis
Self-inflicted lesions on withers, mane, tail, face
Hair loss, excoriation, crusting and scaling, eventually hyperkeratosis and thickening
Which parasite transmits leishmaniasis in dogs?
Sandflies
Which are the 2 main genera of Tabanidae?
Tabanus and Haematopota
Which anthelmintics would you use to treat Gasterophilus spp?
Ivermectin or moxidectin
What are the 3 species of Gasterophilus?
G. intestinalis
G. nasalis
G. haemorrhoidalis
How long is the Chorioptes life cycle? (horse mite)
3 weeks